Study Background:Moringa oleifera, (miracle tree), has been used in the treatment of numerous diseases. Moringa has been the subject of intensive scientific research; however, there have been scanty information on its sub-acute effect on the kidneys. Aims: This work was done to investigate the histological and biochemical effect of M. oleifera on the heart and kidneys of adult Wistar rats. Settings and Design: Twenty-eight adult healthy rats were used for this study. The rats were divided into 4 groups of 7 per group and fed with pellets and water ad libitum. Group A served as the control, Group B were fed with 500 mg/kg of ethanolic extract of Moringa leaf, Group C with 1000 mg/kg while Group D were fed with 1500 mg/kg body weight. Methods and Material: Doses were administered once daily using oral gavage for 28 days. Before the time of sacrificing the animals, blood samples were collected into plain test tubes and the animals anesthetized before sacrifice. Necropsy was performed and the tissues (heart and kidney) processed and stained using Hematoxylin and Eosin staining techniques. Serum electrolyte (sodium and potassium), urea, creatinine, creatine kinase, and lactate dehydrogenase were analyzed for. Results: There were significant increases in urea and potassium in the 1000 mg/kg (41.26 ± 16.89 and 10.52 ± 1.48) and 1500 mg/kg (44.23 ± 17.49 and 13.82 ± 1.57) treated animals when compared with the control (21.47 ± 16.33 and 4.54 ± 1.09). Histo-architecture of the kidneys showed glomerula atrophy in the 1000 mg/kg and 1500 mg/kg treated rats which is indicative of intrinsic renal damage. There were no noticeable structural damage on the heart. Conclusions: The result showed that M. oleifera may be toxic to the kidneys at concentrations higher than 1000 mg/kg.

Plants have played an important role in maintaining health and quality of human life for thousands of years and have served humans well as valuable components of medicines, seasonings, beverages, cosmetics, and dyes.[1] Herbal medicine is based on the premise that plants contain natural substances that can promote health and alleviate illness.[2]Moringa oleifera is one of such plant, having a multipurpose use, either as a vegetable, spice, a source of cooking, cosmetic oil, or as a medicinal plant.[3]M. oleifera grows across Nigeria and is known by local names that vary between ethnic groups.[4] It is called Zogale, Zogale gandi and Bagaruwar makka (Hausa), Ewe igbale and Idagbo monoye (Yoruba), Ikwa oyibo (Igbo), and Kabi (Kilba).[5] It is also known as Haakoobisii (Mumuye), Jeghlegede (Tiv), Gegeredi (Idoma), and Gelgedi (Igala).[6]

This study was carried out to investigate the structural and biochemical effect of M. oleifera on the kidneys and heart of rats.

Materials and Methods

This work was done using 28 adult healthy Wistar rats which were between 11 and 12 weeks of age having a weight range between 210 and 240g. The rats were divided into four groups of 7 rats in each group and were allowed to acclimatize for 2 weeks and fed with standard Pfizer-branded rodent feed obtained from Livestock Feed, Nigeria Ltd. ad libitum, and water was available to the rats in water bottles of the downspout type (drinking nozzle facing downward). The acute toxicity test of the ethanolic extracts of M. oleifera showed that no deaths were recorded in rats up to 4500 mg/kg body weight of the extracts The rats were also fed with Moringa extract at different concentrations Group A: Served as the control, Group B: 500 mg/kg, Group C: 1000 mg/kg, and Group D: 1500 mg/kg (which represented one third of the LD50), Group A were only fed with their normal food and water The doses were administered once daily using oral gavage for 28 days at the end of the animals were anesthetized with chloroform, while blood samples were collected through cardiac puncture into plain bottles using 21 gauge needles mounted on a 5 ml syringe. Necropsy was done, and the heart and kidney tissues were excised and fixed in 10% formal saline for histological evaluation.

Result and Discussion

The values from the findings presented in [Table 1] showed significant (P < 0.05) increases in the level of malondialdehyde (MDA) in a dose-dependent fashion detected at 1000 mg/kg and 1500 mg/kg of the treated rats. However, the enzymatic activities of superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) were significantly reduced in a dose-dependent manner at 1000 mg/kg and 1500 mg/kg of the treated rats. There was, however, no significant (P > 0.05) difference in SOD, GSH, CAT activities and MDA level of the eviscerated heart when compared with the control [Table 2].

Table 1: Effect of extract on the kidneys' oxidative status of treated animals

The values from the findings presented in [Table 3] showed statistical significant increases in potassium (10.52 ± 1.48, P = 0.027 and 13.82 ± 1.57, P = 0.019) in the 1000 mg/kg and 1500 mg/kg treated rats, respectively, when compared with the control. There was also a significant increase in Urea (41.26 ± 16.89, P = 0.031 and 44.23 ± 17.49, P = 0.034) in the 1000 mg/kg and 1500 mg/kg treated rats, respectively when compared with the control. These findings are in agreement with Ugwu (2013)[7] who recorded an increase in serum Urea and potassium when increased doses of M. oleifera diet were fed on rats.

Histological findings on the heart tissues [Figure 2] showed no distinct cytoarchitectural distortion, this finding is not in agreement with Prince et al.,[11] who suggested that there is reduced necrosis to a greater extent of the myocytes due to the anti-cardiotoxic action of the phenolic fraction of Moringa, and it has also demonstrated that M. oleifera leaf is cardioprotective to tissues against oxidative stress in rabbits although at a much lower dose.[12],[13] This study agrees with Bharali et al.,[14] who reported that Moringa leaf extract prevents histopathological damage and ultra-structure perturbation caused due to isoproterenol-induced myocardial infarction.

The histological findings of the kidneys show the photomicrograph of a kidney tissue control [Figure 3] with normal cytoarchitecture and the photomicrograph of a 1500mg/kg treated kidney tissue [Figure 1] showing glomerular atrophy.

The histological findings of the heart shows the photomicrograph of a heart a heart tissue control [Figure 4] and the photomicrograph of a 1500mg/kg treated heart tissue [Figure 2], both having normal cytoarchitecture.

Although the consumption of different parts of M. oleifera, including the leaves for various purposes, has been widely accepted, M. oleifera leaf extract was found to cause a significant increase in urea and potassium. The histoarchitecture of the kidneys showed distortions. The result showed that M. oleifera is toxic to the kidneys at concentrations higher than 1000 mg/kg.